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81-601: The Bayuda Desert , located at 18°N 33°E  /  18°N 33°E  / 18; 33 , is in the eastern region of the Sahara Desert , spanning approximately 100,000 km of northeast Sudan north of Omdurman and south of Korti , embraced by the great bend of the Nile in the north, east, and south and limited by the Wadi Muqaddam in the west. The north-to-south-aligned Wadi Abu Dom divides

162-475: A bed of flowers. The three are assumed to have died within 24 hours of each other, but as their skeletons hold no apparent trauma (they did not die violently) and they have been buried so elaborately – unlikely if they had died of a plague – the cause of their deaths is a mystery. Ahaggar Mountains The Hoggar Mountains are home to the Ahaggar National Park , one of the national parks of

243-652: A cold winter climate. Temperatures fall below freezing in the winter. Rainfall is rare and sporadic year-round. However, since the climate is less extreme than in most other areas of the Sahara, the mountains are a major location for biodiversity , including a number of relict species. The Hoggar Mountains are part of the West Saharan montane xeric woodlands ecoregion . Vegetation in this area includes trees such as Vachellia tortilis , Vachellia seyal , myrtle and Tamarix aphylla which are scattered throughout

324-426: A consequence, the weather tends to be sunny, dry and stable with a minimal chance of rainfall. Subsiding, diverging, dry air masses associated with subtropical high-pressure systems are extremely unfavorable for the development of convectional showers. The subtropical ridge is the predominant factor that explains the hot desert climate ( Köppen climate classification BWh ) of this vast region. The descending airflow

405-466: A healthy adult. The Saharan silver ant is unique in that due to the extreme high temperatures of their habitat, and the threat of predators, the ants are active outside their nest for only about ten minutes per day. Dromedary camels and goats are the domesticated animals most commonly found in the Sahara. Because of its qualities of endurance and speed, the dromedary is the favourite animal used by nomads . Human activities are more likely to affect

486-569: A summer rainy season that extends across Africa from east to west. The southern limit of the Sahara is indicated botanically by the southern limit of Cornulaca monacantha (a drought-tolerant member of the Chenopodiaceae ), or northern limit of Cenchrus biflorus , a grass typical of the Sahel. According to climatic criteria, the southern limit of the Sahara corresponds to the 150 mm (5.9 in) isohyet of annual precipitation (this

567-542: A surface feature of Earth, with near-current technology. The Sahara is mainly rocky hamada (stone plateaus); ergs (sand seas – large areas covered with sand dunes ) form only a minor part, contrary to common misconception , but many of the sand dunes are over 180 metres (590 ft) high. Wind or rare rainfall shape the desert features: sand dunes, dune fields, sand seas, stone plateaus, gravel plains ( reg ), dry valleys ( wadi ), dry lakes ( oued ), and salt flats ( shatt or chott ). Unusual landforms include

648-649: Is a famous and often visited point where Charles de Foucauld built a hermitage in 1911. The highlands are believed to be one of the main sources of the Tamanrasset River , an ancient river that flowed during the African humid period , and named after the main city near the Hoggar Mountains, Tamanrasset , built in a desert valley or wadi that was part of the ancient watercourse. The Hoggar Mountains range typically experiences hot summers, with

729-660: Is a long-term average, since precipitation varies annually). Important cities located in the Sahara include Nouakchott , the capital of Mauritania; Tamanrasset , Ouargla , Béchar , Hassi Messaoud , Ghardaïa , and El Oued in Algeria; Timbuktu in Mali; Agadez in Niger; Ghat in Libya; and Faya-Largeau in Chad. The Sahara is the world's largest hot desert . It is located in

810-422: Is a north African gazelle that can also go for a long time without water. Other notable gazelles include the rhim gazelle and dama gazelle . The Saharan cheetah ( northwest African cheetah ) lives in Algeria, Togo , Niger, Mali, Benin , and Burkina Faso . There remain fewer than 250 mature cheetahs, which are very cautious, fleeing any human presence. The cheetah avoids the sun from April to October, seeking

891-629: Is a prehistoric industry, or domain, that existed between 10,000 and 8,000 years ago in the Sahara, during the Neolithic Subpluvial . Human remains from this culture were found in 2000 at a site known as Gobero , located in Niger in the Ténéré Desert . The site is known as the largest and earliest grave of Stone Age people in the Sahara. The Kiffians were skilled hunters . Bones of many large savannah animals that were discovered in

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972-465: Is associated with high rates of wind-blown mineral dust, and these dust levels are found as expected in marine cores from the north tropical Atlantic. But around 12,500 BCE the amount of dust in the cores in the Bølling / Allerød phase suddenly plummets and shows a period of much wetter conditions in the Sahara, indicating a Dansgaard-Oeschger (DO) event (a sudden warming followed by a slower cooling of

1053-428: Is at 2,908 m (9,541 ft). The mountains are primarily composed of metamorphic rock approximately 2 billion years old, although there are areas where more recent volcanic activity has laid down much newer rock. Several of the more dramatic peaks, such as Ilamen, are the result of erosion wearing away extinct volcano domes, leaving behind the more resistant material that plugged the volcanic cones. Assekrem

1134-403: Is estimated to include five hundred species of plants, which is extremely low considering the huge extent of the area. Plants such as acacia trees, palms, succulents, spiny shrubs, and grasses have adapted to the arid conditions, by growing lower to avoid water loss by strong winds, by storing water in their thick stems to use it in dry periods, by having long roots that travel horizontally to reach

1215-705: Is evident from extant rock paintings dating to 6000 BC. The Hoggar Massif is the land of the Kel Ahaggar Tuareg . The tomb of Tin Hinan , the woman believed to be the matriarch of the Tuareg, is located at Abalessa , an oasis near Tamanrasset. The hermitage of Charles de Foucauld , which continues to be inhabited by a few Catholic monks, is at the top of the Assekrem plateau in the Hoggar Mountains. Underground atomic tests were conducted by France in

1296-667: Is the strongest and the most effective over the eastern part of the Great Desert, in the Libyan Desert: this is the sunniest, driest and the most nearly "rainless" place on the planet, rivaling the Atacama Desert , lying in Chile and Peru . The rainfall inhibition and the dissipation of cloud cover are most accentuated over the eastern section of the Sahara rather than the western. The prevailing air mass lying above

1377-422: Is very unreliable and erratic in the Sahara as it may vary considerably year by year. In full contrast to the negligible annual rainfall amounts, the annual rates of potential evaporation are extraordinarily high, roughly ranging from 2,500 millimetres (100 in) per year to more than 6,000 millimetres (240 in) per year in the whole desert. Nowhere else on Earth has air been found as dry and evaporative as in

1458-543: The Adrar of Mauritania and a value of 75 °C (167 °F) has been measured in Borkou , northern Chad. Due to lack of cloud cover and very low humidity, the desert usually has high diurnal temperature variations between days and nights. However, it is a myth that the nights are especially cold after extremely hot days in the Sahara. On average, nighttime temperatures tend to be 13–20 °C (23–36 °F) cooler than in

1539-488: The Algerian Desert called Bou Bernous , at an elevation of 378 metres (1,240 ft) above sea level, and only Death Valley, California rivals it. Other hot spots in Algeria such as Adrar , Timimoun , In Salah , Ouallene , Aoulef , Reggane with an elevation between 200 and 400 metres (660 and 1,310 ft) above sea level get slightly lower summer average highs, around 46 °C (114.8 °F) during

1620-765: The Late Pleistocene Iberomaurusians , early Holocene Capsians , and mid-Holocene Mechta groups, whereas the Tenerian crania are more like those of Mediterranean groups. Graves show that the Tenerians observed spiritual traditions, as they were buried with artifacts such as jewelry made of hippo tusks and clay pots. The most interesting find is a triple burial, dated to 5300 years ago, of an adult female and two children, estimated through their teeth as being five and eight years old, hugging each other. Pollen residue indicates they were buried on

1701-904: The Nile Valley in Egypt and the Sudan . It stretches from the Red Sea in the east and the Mediterranean in the north to the Atlantic Ocean in the west, where the landscape gradually changes from desert to coastal plains. To the south it is bounded by the Sahel , a belt of semi-arid tropical savanna around the Niger River valley and the Sudan region of sub-Saharan Africa . The Sahara can be divided into several regions, including

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1782-756: The Richat Structure in Mauritania. Several deeply dissected mountains, many volcanic, rise from the desert, including the Aïr Mountains , Ahaggar Mountains , Saharan Atlas , Tibesti Mountains , Adrar des Iforas , and the Red Sea Hills . The highest peak in the Sahara is Emi Koussi , a shield volcano in the Tibesti range of northern Chad. The central Sahara is hyperarid , with sparse vegetation. The northern and southern reaches of

1863-474: The horse latitudes under the subtropical ridge , a significant belt of semi-permanent subtropical warm-core high pressure where the air from the upper troposphere usually descends, warming and drying the lower troposphere and preventing cloud formation. The permanent absence of clouds allows unhindered light and thermal radiation. The stability of the atmosphere above the desert prevents any convective overturning, thus making rainfall virtually non-existent. As

1944-455: The African continent. If all areas with a mean annual precipitation of less than 250 mm (9.8 in) were included, the Sahara would be 11 million square kilometres (4,200,000 sq mi). It is one of three distinct physiographic provinces of the African massive physiographic division . The Sahara is so large and bright that, in theory, it could be detected from other stars as

2025-417: The African humid period. At its largest extent, sometime before 5000 BCE, Lake Mega-Chad was the largest of four Saharan paleolakes, and is estimated to have covered an area of 350,000 km . The Sahara pump theory describes this cycle. During periods of a wet or " Green Sahara ", the Sahara becomes a savanna grassland and various flora and fauna become more common. Following inter-pluvial arid periods,

2106-638: The Bayuda Desert into the eastern Bayuda Volcanic Field and the western ochre -colored sand-sheets scattered with rocky outcrop. Gold mining occurs today from October to March, as laborers work auriferous quartz found in wadis and shallow mines. These workings are usually in areas previously worked during the New Kingdom of Egypt and the Early Arab Period. In July 2020, it was found that gold hunters had used heavy machinery at

2187-412: The Great Desert the hottest large region in the world, and the hottest place on Earth during summer in some spots. The average high temperature exceeds 38 to 40 °C (100.4 to 104.0 °F) during the hottest month nearly everywhere in the desert except at very high altitudes. The world's highest officially recorded average daily high temperature was 47 °C (116.6 °F) in a remote desert town in

2268-486: The Intertropical Convergence Zone from the south and the annual average rainfall ranges from 100 millimetres (4 in) to 250 millimetres (10 in). For example, Timbuktu, Mali and Agadez , Niger are found in this zone. The vast central hyper-arid core of the desert is virtually never affected by northerly or southerly atmospheric disturbances and permanently remains under the influence of

2349-598: The Jabal Maragha archaeological site, destroying it by digging a huge trench. The gold diggers were arrested and their equipment seized, but they were later released without charges. Throughout the Meroitic civilization , the Bayuda Desert became the lifeline connecting the northern and southern districts of the Kingdom of Kush , with Napata and Meroe as the termini. The king Nastasen Stela provides testament of

2430-523: The Kiffian culture do not exist after 8,000 years ago, as the Sahara went through a dry period for the next thousand years. After this time, the Tenerian culture colonized the area. Gobero was discovered in 2000 during an archaeological expedition led by Paul Sereno , which sought dinosaur remains. Two distinct prehistoric cultures were discovered at the site: the early Holocene Kiffian culture, and

2511-462: The Sahara (birds in particular) such as African silverbill and black-faced firefinch , among others. There are also small desert crocodiles in Mauritania and the Ennedi Plateau of Chad. The deathstalker scorpion can be 10 cm (3.9 in) long. Its venom contains large amounts of agitoxin and scyllatoxin and is very dangerous; however, a sting from this scorpion rarely kills

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2592-472: The Sahara area then reverts to desert conditions and the flora and fauna are forced to retreat northwards to the Atlas Mountains , southwards into West Africa , or eastwards into the Nile Valley . This separates populations of some of the species in areas with different climates , forcing them to adapt , possibly giving rise to allopatric speciation . It is also proposed that humans accelerated

2673-528: The Sahara is strongly influenced by the North Atlantic Oscillation (NAO), with warmer winter temperatures during negative NAO events and cooler winters with more frosts when the NAO is positive. This is because the weaker clockwise flow around the eastern side of the subtropical anticyclone during negative NAO winters, although too dry to produce more than negligible precipitation, does reduce

2754-504: The Sahara is the continental tropical (cT) air mass, which is hot and dry. Hot, dry air masses primarily form over the North-African desert from the heating of the vast continental land area, and it affects the whole desert during most of the year. Because of this extreme heating process, a thermal low is usually noticed near the surface, and is the strongest and the most developed during the summertime. The Sahara High represents

2835-638: The Sahara region. However, at least two instances of snowfall have been recorded in Sahara, in February 1979 and December 2016, both in the town of Ain Sefra . One theory for the formation of the Sahara is that the monsoon in Northern Africa was weakened because of glaciation during the Quaternary period, starting two or three million years ago. Another theory is that the monsoon was weakened when

2916-713: The Tassili n'Ajjer in southeast Algeria. Fossils of dinosaurs , including Afrovenator , Jobaria and Ouranosaurus , have also been found here. The modern Sahara, though, is not lush in vegetation, except in the Nile Valley, at a few oases , and in the northern highlands, where Mediterranean plants such as the olive tree are found to grow. Shifts in Earth's axis increased temperatures and decreased precipitation, which caused an abrupt beginning of North Africa desertification about 5,400 years ago. The Kiffian culture

2997-595: The amount of rainfall received – the Northern (Mediterranean), Central and Southern Zones. There are two transitional zones – the Mediterranean-Sahara transition and the Sahel transition zone. The Saharan flora comprises around 2800 species of vascular plants . Approximately a quarter of these are endemic . About half of these species are common to the flora of the Arabian deserts. The central Sahara

3078-612: The ancient Tethys Sea dried up during the Tortonian period around 7 million years ago. The climate of the Sahara has undergone enormous variations between wet and dry over the last few hundred thousand years, believed to be caused by long-term changes in the North African climate cycle that alters the path of the North African Monsoon – usually southward. The cycle is caused by a 41,000-year cycle in which

3159-578: The area. Other plants may include Citrullus colocynthis and Calotropis procera . Slightly to the west of the Hoggar range, a population of the endangered African wild dog ( Lycaon pictus ) remained viable into the 20th century, but is now thought to be extirpated within this entire region. Relict populations of the West African crocodile persisted in the Hoggar Mountains until the early 20th century. Analysis of collected scat in 2006 showed

3240-421: The atmospheric circulation itself, the desert is made even drier by its geographical configuration and location. Indeed, the extreme aridity of the Sahara is not only explained by the subtropical high pressure: the Atlas Mountains of Algeria, Morocco and Tunisia also help to enhance the aridity of the northern part of the desert. These major mountain ranges act as a barrier, causing a strong rain shadow effect on

3321-616: The climate). The moister Saharan conditions had begun about 12,500 BCE, with the extension of the ITCZ northward in the northern hemisphere summer, bringing moist wet conditions and a savanna climate to the Sahara, which (apart from a short dry spell associated with the Younger Dryas ) peaked during the Holocene thermal maximum climatic phase at 4000 BCE when mid-latitude temperatures seem to have been between 2 and 3 degrees warmer than in

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3402-535: The column's intelligence officer. The Expedition saw the Battle of Abu Klea and the Battle Abu Kru . Sahara Desert The Sahara ( / s ə ˈ h ɑːr ə / , / s ə ˈ h ær ə / ) is a desert spanning across North Africa . With an area of 9,200,000 square kilometres (3,600,000 sq mi), it is the largest hot desert in the world and the third-largest desert overall, smaller only than

3483-437: The country . The tallest peak in the range and Algeria, Mount Tahat , is located in the park area, which covers approximately 450,000 square kilometres (170,000 sq mi). This mountainous region is located about 1,500 km (930 mi) south of the capital, Algiers . The area is largely rocky desert with an average elevation of more than 900 m (3,000 ft) above sea level. The highest peak, Mount Tahat ,

3564-474: The daytime. The smallest variations are found along the coastal regions due to high humidity and are often even lower than a 10 °C (18 °F) difference, while the largest variations are found in inland desert areas where the humidity is the lowest, mainly in the southern Sahara. Still, it is true that winter nights can be cold, as it can drop to the freezing point and even below, especially in high-elevation areas. The frequency of subfreezing winter nights in

3645-469: The desert experiences around three to five months when the average high strictly exceeds 40 °C (104 °F); while in the southern central part of the desert, there are up to six or seven months when the average high temperature strictly exceeds 40 °C (104 °F). Some examples of this are Bilma , Niger and Faya-Largeau, Chad. The annual average daily temperature exceeds 20 °C (68 °F) everywhere and can approach 30 °C (86 °F) in

3726-643: The desert, along with the highlands, have areas of sparse grassland and desert shrub , with trees and taller shrubs in wadis , where moisture collects. In the central, hyperarid region, there are many subdivisions of the great desert: Tanezrouft , the Ténéré , the Libyan Desert , the Eastern Desert , the Nubian Desert and others. These extremely arid areas often receive no rain for years. To

3807-528: The deserts of Antarctica and the northern Arctic . The name "Sahara" is derived from Arabic : صَحَارَى , romanized :  ṣaḥārā /sˤaħaːraː/ , a broken plural form of ṣaḥrā' ( صَحْرَاء /sˤaħraːʔ/ ), meaning "desert". The desert covers much of North Africa , excluding the fertile region on the Mediterranean Sea coast, the Atlas Mountains of the Maghreb , and

3888-531: The drying-out period from 6000 to 2500 BCE by pastoralists overgrazing available grassland. The growth of speleothems (which requires rainwater) was detected in Hol-Zakh, Ashalim , Even-Sid, Ma'ale-ha-Meyshar, Ktora Cracks, Nagev Tzavoa Cave, and elsewhere, and has allowed tracking of prehistoric rainfall. The Red Sea coastal route was extremely arid before 140 and after 115 kya (thousands of years ago). Slightly wetter conditions appear at 90–87 kya, but it still

3969-667: The eastern continental extension of the Azores High , centered over the North Atlantic Ocean . The subsidence of the Sahara High nearly reaches the ground during the coolest part of the year, while it is confined to the upper troposphere during the hottest periods. The effects of local surface low pressure are extremely limited because upper-level subsidence still continues to block any form of air ascent. Also, to be protected against rain-bearing weather systems by

4050-614: The edge of the desert thousands of years ago, since the end of the last glacial period . In the Central Sahara, engraved and painted rock art were created perhaps as early as 10,000 years ago, spanning the Bubaline Period , Kel Essuf Period , Round Head Period , Pastoral Period , Caballine Period , and Cameline Period . The Sahara was then a much wetter place than it is today. Over 30,000 petroglyphs of river animals such as crocodiles survive, with half found in

4131-685: The existence and use of this route, describing his progress across the desert from Meroe to Napata for his coronation. The Bayuda Desert was crossed by the Desert Column of the Gordon Relief Expedition in January 1885 in a failed attempt to relieve the Siege of Khartoum . The Desert Column was led mainly by Major General Sir Herbert Stewart , but after he was mortally wounded, command passed to Brigadier General Charles Wilson ,

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4212-484: The flow of dry, cold air from higher latitudes of Eurasia into the Sahara significantly. The average annual rainfall ranges from very low in the northern and southern fringes of the desert to nearly non-existent over the central and the eastern part. The thin northern fringe of the desert receives more winter cloudiness and rainfall due to the arrival of low pressure systems over the Mediterranean Sea along

4293-699: The habitat in areas of permanent water (oases) or where water comes close to the surface. Here, the local pressure on natural resources can be intense. The remaining populations of large mammals have been greatly reduced by hunting for food and recreation. In recent years development projects have started in the deserts of Algeria and Tunisia using irrigated water pumped from underground aquifers. These schemes often lead to soil degradation and salinization . Researchers from Hacettepe University have reported that Saharan soil may have bio-available iron and also some essential macro and micro nutrient elements suitable for use as fertilizer for growing wheat. People lived on

4374-405: The highest recorded worldwide. The sky is usually clear above the desert, and the sunshine duration is extremely high everywhere in the Sahara. Most of the desert has more than 3,600 hours of bright sunshine per year (over 82% of daylight hours), and a wide area in the eastern part has over 4,000 hours of bright sunshine per year (over 91% of daylight hours). The highest values are very close to

4455-551: The hottest months of the year. Salah, well known in Algeria for its extreme heat, has average high temperatures of 43.8 °C (110.8 °F), 46.4 °C (115.5 °F), 45.5 °C (113.9 °F) and 41.9 °C (107.4 °F) in June, July, August and September respectively. There are even hotter spots in the Sahara, but they are located in extremely remote areas, especially in the Azalai , lying in northern Mali. The major part of

4536-433: The hottest regions year-round. However, most of the desert has a value in excess of 25 °C (77 °F). Sand and ground temperatures are even more extreme. During daytime, the sand temperature is extremely high: it can easily reach 80 °C (176 °F) or more. A sand temperature of 83.5 °C (182.3 °F) has been recorded in Port Sudan . Ground temperatures of 72 °C (161.6 °F) have been recorded in

4617-406: The last glacial period , the Sahara was much larger than it is today, extending south beyond its current boundaries. The end of the glacial period brought more rain to the Sahara, from about 8000 BCE to 6000 BCE, perhaps because of low pressure areas over the collapsing ice sheets to the north. Once the ice sheets were gone, the northern Sahara dried out. In the southern Sahara, the drying trend

4698-458: The late nineteenth century, The hypothesis was later formally proposed and tested by the meteorologist John Kutzbach in 1981. Kutzbach's ideas about the impacts of insolation on global monsoonal patterns have become widely accepted today as the underlying driver of long-term monsoonal cycles. Kutzbach never formally named his hypothesis and as such it is referred to here as the " Orbital Monsoon Hypothesis " as suggested by Ruddiman in 2001. During

4779-446: The leeward side by dropping much of the humidity brought by atmospheric disturbances along the polar front which affects the surrounding Mediterranean climates. The primary source of rain in the Sahara is the Intertropical Convergence Zone , a continuous belt of low-pressure systems near the equator which bring the brief, short and irregular rainy season to the Sahel and southern Sahara. Rainfall in this giant desert has to overcome

4860-419: The maximum area of water and to find any surface moisture, and by having small thick leaves or needles to prevent water loss by evapotranspiration . Plant leaves may dry out totally and then recover. Several species of fox live in the Sahara including: the fennec fox , pale fox and Rüppell's fox . The addax , a large white antelope , can go nearly a year in the desert without drinking. The dorcas gazelle

4941-437: The middle Holocene Tenerian culture . The post-Kiffian desiccation lasted until around 4600 BCE, when the earliest artefacts associated with the Tenerians have been dated to. Some 200 skeletons have been discovered at Gobero. The Tenerians were considerably shorter in height and less robust than the earlier Kiffians. Craniometric analysis also indicates that they were osteologically distinct. The Kiffian skulls are akin to those of

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5022-409: The north, the Sahara skirts the Mediterranean Sea in Egypt and portions of Libya, but in Cyrenaica and the Maghreb , the Sahara borders the Mediterranean forest, woodland, and scrub eco-regions of northern Africa, all of which have a Mediterranean climate characterized by hot summers and cool and rainy winters. According to the botanical criteria of Frank White and geographer Robert Capot-Rey,

5103-422: The northern limit of the Sahara corresponds to the northern limit of date palm cultivation and the southern limit of the range of esparto , a grass typical of the Mediterranean climate portion of the Maghreb and Iberia . The northern limit also corresponds to the 100 mm (3.9 in) isohyet of annual precipitation. To the south, the Sahara is bounded by the Sahel, a belt of dry tropical savanna with

5184-407: The opposite is true, with decreased annual precipitation and less vegetation resulting in a phase of the Sahara climate cycle known as the "desert Sahara". The idea that changes in insolation (solar heating) caused by long-term changes in Earth's orbit are a controlling factor for the long-term variations in the strength of monsoon patterns across the globe was first suggested by Rudolf Spitaler in

5265-419: The physical and atmospheric barriers that normally prevent the production of precipitation. The harsh climate of the Sahara is characterized by: extremely low, unreliable, highly erratic rainfall; extremely high sunshine duration values; high temperatures year-round; negligible rates of relative humidity ; a significant diurnal temperature variation ; and extremely high levels of potential evaporation which are

5346-401: The polar front, although very attenuated by the rain shadow effects of the mountains and the annual average rainfall ranges from 100 millimetres (4 in) to 250 millimetres (10 in). For example, Biskra , Algeria, and Ouarzazate , Morocco, are found in this zone. The southern fringe of the desert along the border with the Sahel receives summer cloudiness and rainfall due to the arrival of

5427-407: The presence of the Northwest African cheetah in the region. Between August 2008 and November 2010, four individuals were recorded by camera traps . A single cheetah was filmed and photographed by Algerian naturalists in 2020 in the national park in the Atakor volcanic field whose peaks approach a height of 3,000 metres (9,800 ft). The park also contains a population of herbivores such as

5508-406: The recent past. Analysis of Nile River deposited sediments in the delta also shows this period had a higher proportion of sediments coming from the Blue Nile , suggesting higher rainfall also in the Ethiopian Highlands . This was caused principally by a stronger monsoonal circulation throughout the sub-tropical regions, affecting India, Arabia and the Sahara. Lake Victoria only recently became

5589-513: The saharan subspecies of the barbary sheep and the Dorcas gazelle . The park has been designated an Important Bird Area (IBA) by BirdLife International because it supports significant populations of spotted , crowned and Lichtenstein's Sandgrouse , Pharaoh eagle-owls , pallid harriers , greater hoopoe-larks , bar-tailed and desert larks , pale rock martins , fulvous babblers , white-crowned and mourning wheatears , desert sparrows and trumpeter finches . Prehistoric settlement

5670-451: The same area suggest that they lived on the shores of a lake that was present during the Holocene Wet Phase, a period when the Sahara was verdant and wet. The Kiffian people were tall, standing over six feet in height. Craniometric analysis indicates that this early Holocene population was closely related to the Late Pleistocene Iberomaurusians and early Holocene Capsians of the Maghreb, as well as mid-Holocene Mechta groups. Traces of

5751-412: The scale of the Nile floods between 2700 and 2100 BCE. The Sahara comprises several distinct ecoregions . With their variations in temperature, rainfall, elevation, and soil, these regions harbor distinct communities of plants and animals. The flora of the Sahara is highly diversified based on the bio-geographical characteristics of this vast desert. Floristically , the Sahara has three zones based on

5832-573: The shelter of shrubs such as balanites and acacias. They are unusually pale. The other cheetah subspecies ( northeast African cheetah ) lives in Chad, Sudan and the eastern region of Niger. However, it is currently extinct in the wild in Egypt and Libya. There are approximately 2000 mature individuals left in the wild. Other animals include the monitor lizards , hyrax , sand vipers , and small populations of African wild dog , in perhaps only 14 countries and red-necked ostrich . Other animals exist in

5913-596: The source of the White Nile and dried out almost completely around 15 kya. The sudden subsequent movement of the ITCZ southwards with a Heinrich event (a sudden cooling followed by a slower warming), linked to changes with the El Niño-Southern Oscillation cycle, led to a rapid drying out of the Saharan and Arabian regions, which quickly became desert. This is linked to a marked decline in

5994-561: The strongest anticyclonic weather regime, and the annual average rainfall can drop to less than 1 millimetre (0.04 in). In fact, most of the Sahara receives less than 20 millimetres (0.8 in). Of the 9,000,000 square kilometres (3,500,000 sq mi) of desert land in the Sahara, an area of about 2,800,000 square kilometres (1,100,000 sq mi) (about 31% of the total area) receives an annual average rainfall amount of 10 millimetres (0.4 in) or less, while some 1,500,000 square kilometres (580,000 sq mi) (about 17% of

6075-611: The theoretical maximum value. A value of 4300 hours (98%) of the time would be recorded in Upper Egypt ( Aswan , Luxor ) and in the Nubian Desert ( Wadi Halfa ). The annual average direct solar irradiation is around 2,800 kWh/(m year) in the Great Desert. The Sahara has a huge potential for solar energy production. The high position of the Sun, the extremely low relative humidity, and the lack of vegetation and rainfall make

6156-472: The tilt of the earth changes between 22° and 24.5°. At present, it is in a dry period, but it is expected that the Sahara will become green again in 15,000 years. When the North African monsoon is at its strongest, annual precipitation and subsequent vegetation in the Sahara region increase, resulting in conditions commonly referred to as the " green Sahara ". For a relatively weak North African monsoon,

6237-478: The total area) receives an average of 5 millimetres (0.2 in) or less. The annual average rainfall is virtually zero over a wide area of some 1,000,000 square kilometres (390,000 sq mi) in the eastern Sahara comprising deserts of: Libya, Egypt and Sudan ( Tazirbu , Kufra , Dakhla , Kharga , Farafra , Siwa , Asyut , Sohag , Luxor, Aswan, Abu Simbel , Wadi Halfa) where the long-term mean approximates 0.5 millimetres (0.02 in) per year. Rainfall

6318-750: The western Sahara, the central Ahaggar Mountains , the Tibesti Mountains , the Aïr Mountains , the Ténéré desert, and the Libyan Desert . For several hundred thousand years, the Sahara has alternated between desert and savanna grassland in a 20,000-year cycle caused by the precession of Earth's axis (about 26,000 years) as it rotates around the Sun, which changes the location of the North African monsoon . The Sahara covers large parts of Algeria , Chad , Egypt , Libya , Mali , Mauritania , Niger , Western Sahara and Sudan , and parts of southern Morocco and Tunisia . It covers 9 million square kilometres (3,500,000 sq mi), 31% of

6399-403: Was initially counteracted by the monsoon , which brought rain further north than it does today. By around 4200 BCE, however, the monsoon retreated south to approximately where it is today, leading to the gradual desertification of the Sahara. The Sahara is now as dry as it was about 13,000 years ago. Lake Chad is the remnant of a former inland sea, paleolake Mega-Chad, which existed during

6480-470: Was just one tenth the rainfall around 125 kya. In the southern Negev Desert speleothems did not grow between 185 and 140 kya ( MIS 6), 110–90 (MIS 5.4–5.2), nor after 85 kya nor during most of the interglacial period (MIS 5.1), the glacial period and Holocene . This suggests that the southern Negev was arid-to-hyper-arid in these periods. During the Last Glacial Maximum (LGM) the Sahara

6561-575: Was more extensive than it is now with the extent of the tropical forests being greatly reduced, and the lower temperatures reduced the strength of the Hadley Cell . This is a climate cell which causes rising tropical air of the Inter-Tropical Convergence Zone (ITCZ) to bring rain to the tropics, while dry descending air, at about 20 degrees north , flows back to the equator and brings desert conditions to this region. It

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